A rubber hose has been conventionally manufactured by extruding a curable rubber from an extruder onto a mandrel made from an organic polymer to form a rubber layer, and curing the rubber layer by heating from the outside of the rubber layer. As a method for this end, a so-called batch method has heretofore been employed, which comprises extruding, on a mandrel, products in a continuous length having a curable rubber layer, and heating the same in the state of a bundle in a steam cure room for curing. This conventional method, nevertheless, is associated with the following problems.
(1) Low production efficiency because of non-continuous production. PA0 (2) Possible batch-dependent variations in the properties and quality of the hose. PA0 (3) Curling or bundling trace on a rubber hose after curing, due to heat-curing of extrusion products in a bundle state.
A rubber hose is used for various applications where high dimensional precision is required. The above-mentioned problems (2) and (3) often cause a failure to satisfy the requirement of high dimensional precision. Moreover, since the state and degree of curling (bundling trace) of the rubber hose can vary, attachment of a splicing fitting on both ends of a rubber hose may become difficult.
Although the demand for a continuous manufacture of rubber hose has long been felt in this field of art to solve the problems associated with the batch method, a continuous manufacture of rubber hose has not been industrially realized, as far as the present inventors are aware. This is because a rubber hose is generally thick, so that external heating from the outside of a rubber layer takes a long time until the thick rubber layer is sufficiently cured to the inside thereof, which in turn leads to the need of a large-scale continuous manufacturing apparatus and a large housing structure therefor.